/*
 * Copyright (C) 2007-2010 Geometer Plus <contact@geometerplus.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

package org.geometerplus.fbreader.formats.fb2;

import java.io.*;

import org.geometerplus.zlibrary.core.image.ZLSingleImage;

import org.geometerplus.fbreader.Paths;

final class Base64EncodedImage extends ZLSingleImage {
	private static int ourCounter;

	static void resetCounter() {
		ourCounter = 0;
	}

	private final String myDirName;
	private final int myFileNumber;
	private OutputStreamWriter myStreamWriter;
	private boolean myIsDecoded;
	
	public Base64EncodedImage(String contentType) {
		// TODO: use contentType
		super(contentType);
		myDirName = Paths.cacheDirectory().intern();
		new File(myDirName).mkdirs();
		myFileNumber = ourCounter++;
		try {
			myStreamWriter = new OutputStreamWriter(new FileOutputStream(myDirName + "/image" + myFileNumber), "UTF-8");
		} catch (IOException e) {
		}
	}

	private static byte decodeByte(byte encodedByte) {
		switch (encodedByte) {
			case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
			case 'G': case 'H': case 'I': case 'J': case 'K': case 'L':
			case 'M': case 'N': case 'O': case 'P': case 'Q': case 'R':
			case 'S': case 'T': case 'U': case 'V': case 'W': case 'X':
			case 'Y': case 'Z':
				return (byte)(encodedByte - 'A');
			case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
			case 'g': case 'h': case 'i': case 'j': case 'k': case 'l':
			case 'm': case 'n': case 'o': case 'p': case 'q': case 'r':
			case 's': case 't': case 'u': case 'v': case 'w': case 'x':
			case 'y': case 'z':
				return (byte)(encodedByte - 'a' + 26);
			case '0': case '1': case '2': case '3': case '4':
			case '5': case '6': case '7': case '8': case '9':
				return (byte)(encodedByte - '0' + 52);
			case '+':
				return 62;
			case '/':
				return 63;
			case '=':
				return 64;
		}
		return -1;
	}

	public byte[] byteData() {
		try {
			decode();
			final File file = new File(myDirName + "/dimage" + myFileNumber);
			final byte[] data = new byte[(int)file.length()];
			final FileInputStream stream = new FileInputStream(file);
			stream.read(data);
			stream.close();
			return data;
		} catch (IOException e) {
			return null;
		}
	}
	
	private void decode() throws IOException {
		if (myIsDecoded) {
			return;
		}
		myIsDecoded = true;

		int dataLength;
		byte[] encodedData;
		FileOutputStream outputStream;
		
		final File file = new File(myDirName + "/image" + myFileNumber);
		outputStream = new FileOutputStream(myDirName + "/dimage" + myFileNumber);
		dataLength = (int)file.length();
		final FileInputStream inputStream = new FileInputStream(file);
		encodedData = new byte[dataLength];
		inputStream.read(encodedData);
		inputStream.close();
		file.delete();

		final byte[] data = new byte[dataLength * 3 / 4 + 4];
		int dataPos = 0;
		for (int pos = 0; pos < dataLength; ) {
			byte n0 = -1, n1 = -1, n2 = -1, n3 = -1;
			while ((pos < dataLength) && (n0 == -1)) {
				n0 = decodeByte(encodedData[pos++]);
			}
			while ((pos < dataLength) && (n1 == -1)) {
				n1 = decodeByte(encodedData[pos++]);
			}
			while ((pos < dataLength) && (n2 == -1)) {
				n2 = decodeByte(encodedData[pos++]);
			}
			while ((pos < dataLength) && (n3 == -1)) {
				n3 = decodeByte(encodedData[pos++]);
			}
			data[dataPos++] = (byte)(n0 << 2 | n1 >> 4);
			data[dataPos++] = (byte)(((n1 & 0xf) << 4) | ((n2 >> 2) & 0xf));
			data[dataPos++] = (byte)(n2 << 6 | n3);
		}
		outputStream.write(data, 0, dataPos);
		outputStream.close();
	}
	
	void addData(char[] data, int offset, int length) {
		if (myStreamWriter != null) {
			try {
				myStreamWriter.write(data, offset, length);
			} catch (IOException e) {
			}
		}
	}

	void close() {
		try {
			myStreamWriter.close();
		} catch (IOException e) {
		}
	}
}
